Structure and chemical composition of cell wall, cytoplasm membrane, protoplasts, spheroplasts the cytoplasm, nuclear material. The bacterial cell wall is a rigid structure surrounding the cytoplasmic membrane that gives the cell its shape, mechanical strength, and protection against osmotic pressure.It is the primary feature distinguishing Gram-positive and Gram-negative bacteria. B. Functions C. Structure and Chemical…
Size of Bacteria Bacteria are microscopic unicellular organisms that vary greatly in size depending on the species and environmental conditions. Examples: Significance:The small size ensures a high surface area-to-volume ratio, facilitating efficient nutrient uptake, waste removal, and rapid growth. 2. Shape of Bacteria The shape (morphology) of bacteria is genetically determined and maintained by the…
Morphology and fine structure of bacteria are microscopic, single-celled prokaryotic organisms that lack a true nucleus and membrane-bound organelles.They are among the earliest and simplest forms of life, yet they exhibit remarkable structural diversity and metabolic versatility. Understanding the morphology (shape and size) and fine structure (internal and external components) of bacteria is essential for…
Viruses are obligate intracellular parasites, meaning they can multiply only inside living cells.When a virus infects a host cell, it can cause a wide range of effects — from no visible damage (latent infection) to cell destruction or transformation into a cancer cell. The interaction between a virus and its host cell is therefore central…
Animal viruses are infectious agents that replicate only inside animal cells, including those of humans. They contain either DNA or RNA as their genetic material and depend entirely on the host cell’s metabolic machinery for replication. For understanding their diversity, behavior, and medical significance, viruses are classified systematically and cultivated using living systems. 2. Classification…
Viruses are submicroscopic infectious agents that can multiply only inside living host cells (animals, plants, bacteria, or fungi).They are non-cellular, consisting mainly of nucleic acid and protein, and lack independent metabolic machinery.Although extremely small (20–300 nm), viruses are among the most abundant biological entities on Earth and play key roles in disease, genetics, and molecular…
Adaptations of Fish to Abiotic Environmental Factors Fish are aquatic vertebrates that live in diverse habitats — from cold, deep oceans to warm, shallow rivers. To survive, they have developed remarkable physiological, morphological, and behavioral adaptations to cope with varying abiotic factors of their environment. 1. Adaptation to Density of Water: Density refers to how…
Fish live in aquatic ecosystems (freshwater, marine, estuarine) that vary widely in abiotic (non-living) environmental factors, such as: Temperature Salinity Oxygen availability Water currents Light penetration pH and chemical composition To survive, grow, and reproduce successfully, fish have evolved a variety of morphological, physiological, and behavioral adaptations that allow them to cope with these changing…
Viruses are acellular, ultramicroscopic infectious entities that occupy a unique position between living and non-living matter. They are obligate intracellular parasites, meaning they can multiply only within living host cells by utilizing the host’s metabolic machinery. They infect all forms of life — animals, plants, bacteria (bacteriophages), fungi, algae, and even other viruses (virophages). Despite…
Bacteriophages (or simply phages) are viruses that infect bacteria. They replicate inside bacterial host cells, using the host’s enzymes, ribosomes, and metabolic machinery to produce new virus particles. Phage replication follows two main types of life cycles: 2. Types of Replication Cycles A. Lytic Cycle (Virulent Cycle): Carried out by virulent phages such as T4…
Phages (short for bacteriophages) are viruses that infect prokaryotic cells, mainly bacteria and archaea. The term bacteriophage literally means “bacteria eater.” Similarly, phages of other protists refer to viruses that infect unicellular eukaryotes such as protozoa and algae. These are less studied but equally important in ecology and evolutionary biology. Phages play a critical role…
A virus is a submicroscopic infectious agent that can replicate only inside the living cells of other organisms. Viruses infect animals, plants, fungi, bacteria (bacteriophages), and even archaea.They are non-cellular, meaning they are not considered true living organisms, but they possess some characteristics of life, such as reproduction and mutation. The word virus comes from…
Nomenclature in Microbiology Nomenclature = the system of naming microorganisms in a standardized way so scientists worldwide can communicate clearly. a) Binomial System (developed by Linnaeus, adopted in microbiology) b) Rules of Nomenclature c) Strain Designation 2. Bergey’s Manual of Systematic Bacteriology Bergey’s Manual is the authoritative reference for bacterial classification and identification. a) History…
Microorganisms are extremely diverse and often invisible to the naked eye. To study them scientifically, we need to characterize (describe their properties) and identify (determine their exact taxonomic position). 1. Characterization of Microorganisms Characterization means describing the morphological, physiological, biochemical, genetic, and ecological features of microbes. a) Morphological Characteristics b) Physiological and Metabolic Characteristics c)…
1. Microbial Evolution Evolution in microbiology refers to how microorganisms originated, diversified, and adapted to various environments. a) Origin of Microorganisms b) Major Events in Microbial Evolution c) Evolutionary Forces in Microbes 2. Systematics in Microbiology Systematics = Study of the diversity of organisms and their evolutionary relationships. Components of Microbial Systematics Approaches in Microbial…
